Antidetonant liquid injection apparatus



Sept 2 0, W49" D. E. DAHLE ZAMJW ANTIDETONANT LIQUID INJECTION APPARATUS Filed Sept. 21, 1945 FIG. 1,

INVENTOR.

DONALD E DAH LE WW W ATTORNEY.

Patented Sept. 20, 1949 ANTIDETONANT LIQUID INJECTION APPARATUS Donald E. Dahle, United States Navy Application September 21, 1945, Serial No. 617,893

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 O. G. 757) 1 Claim.

This invention relates to new and useful improvements in anti-detonant liquid injection systems for internal combustion engines, and more particularly to anti-detonant injection systems for internal combustion engines employing float type fuel carburetors.

The amount of antl-detonant liquid necessary to be injected into an internal combustion engine to suppress detonation is approximately twenty per cent of the total liquid charge to the engine; that is the total amount of fuel and anti-detonant injected. However, the percentage of antidetonant liquid should vary with the brake mean effective pressure (with no flow at light loads) and is further dependent upon flame speed, the requirement being inversely proportional to the engine speed.-

It has been attempted heretofore to provide anti-detonant liquid injection for internal combustion engines employing float type carburetors. However, while these attempts may be said to compensate for the engine brake mean effective pressure, they do not meter the anti-detonant liquid upon an airflow basis and furthermore, do not compensate for engine speed.

Accordingly, and with the foregoing in mind, the principal object of the present invention is to provide a novel anti-detonant liquid inject on system for internal combustion engines having float type carburetors which not only compensates for the engine brake mean effective pressure, but which also operates to meter antidetonant liquid upon the basis of airflow and engine speed.

Another object of the present invention is to provide an anti-detonant liquid injection system of the stated character which is entirely automatic in operation.

A further object of the present invention is to provide an anti-detonant liquid injection system having the features and characteristics set forth which is of relatively simplified and inexpensive construction, and highly efficient and fool-proof in operation and use.

These and other objects of the invention, and the various features and details of the construction and operation thereof, are hereinafter fully set forth and described with reference to the accompanying drawing, in which:

Fig. 1 is a diagrammatic View showing an antidetonant injection system embodying the present invention in association with a float type carburetor and fuel system of an internal combustion engine.

Fig. 2 is an enlarged fragmentary view in sec- 2 tion of the portion bounded by the dot-dash circle A in Fig. 1; and

Fig. 3 is an enlarged View in section of the portion bounded by the dot-dash circle B in Fig. 1.

Referring now to the drawing, and more particularly to Fig. 1 thereof, the present invention is shown in conjunction with a conventional type fuel supply system of an internal combustion engine comprising the usual downdraft air intake duct 1, air filter 2, and float type fuel carburetor 3 from which fuel is supplied through a tube 4 and injected into the duct l at the throat of a venturi 5 for mixture with the intake air in the customary manner. The duct l is provided with the usual choke control 6 in advance of the venturi 5, and the conventional throttle 1 between the venturi 5 and the engine intake manifold 8. The foregoing apparatus functions in the conventional and well known manner to supply the desired fuel-air mixture to the manifold 8 for proper operation of the internal combustion engine with which associated.

In accordance with the present invention, antidetonant' liquid such as, for example, water or a water-alcohol mixture, is injected into the duct l at the throat of the venturi 5 and from a tube 9 which leads from a float chamber I0 containing anti-detonant liquid II. The flow of liquid from float chamber l0 through the tube 9 is metered by a jet I2 of predetermined cross-sectional area.

provided at the inlet end of said tube 9 (see Fig. 2). The liquid II is supplied to the chamber ill from a suitable supply tank l3 through a pipe 14 which leads therefrom into the top of the float chamber Ill as shown, the pipe l4 having therein a suitable shut-oil valve I5.

Flow of anti-detonant from the tank l3 through pipe l4 into the float chamber I0 is controlled by a valve I! operated by a suitable float device I8 which is constructed and arranged to maintain the anti-detonant liquid H in said float chamber ID at a predetermined constant level therein and with a reasonable amount of space thereabove. In this connection, it is to be noted that the float chamber I0 is positioned with respect to the fuel supply system of the engine so that the level of the anti-detonant liquid II in the chamber I0 is slightly below the level of the throat of the venturi 5 in the fuel duct l where the anti-detonant liquid is injected.

In the top of the float chamber Hi, there is provided a suitable vent 20, having a jet 2 I, which leads to the atmosphere, and leading from the space in the chamber 10 through a jet 22 located above the level of the liquid H (see Fig. 3), there 3 is a conduit 23 which extends to and has its other end in communication with the interior or the throat of a second venturi 24 that is disposed in the fuel supply system in a section of pipe 26 inserted intermediate the duct I and the inlet to the engine intake manifold 8 as shown. It is to be noted that the design of the flow areas of the jets 2I and 22, as well as of the et I2, is critical for any given internal combustion engine installation with which employed, and hence, for different engine installations, these ets, of course, will be specially designed just as it is necessary to specially design the jets of fuel carburetion systems to meet the requirements for different engines.

By positioning the venturi 24 downstream of the throttle and adjacent the inlet to the manifold 8, the difference between the suction pressure at the venturi 24 and the static pressure in the manifold 8 will vary as the square of the speed of the internal combustion engine. However, according to the present invention, the venturi 24 is designed to provide a throat of sufiicient area so that the difierence between the suction pressure at venturi 24 and the static pressure in manifold 8 Wil be negligible except at relatively high engine speeds. Therefore, the suction pressure at venturi 24 will be substantially equal to the manifold static pressure except at relatively high engine speeds, with the result that the suction pressure at said venturi 24 will be proportioned to, and provide a measurement of,'the speed of the internal combustion engine. In addition, the manifold absolute pressure is a function of the brake mean effective pressure, and since the suction pressure at the venturi 24 is substantially equal to the static pressure in manifold 8, the suction pressure at the venturi 24 likewise is a function, and affords a measurement, of the engine brake mean effective pressure.

Apart from the foregoing, the pressure across the jet I2 at the inlet of the tube 9 is the difference between atmospheric pressure (through vent 20) upon the surface of the liquid II in the float chamber I and the absolute pressure at the throat of the venturi minus the small head difference between the level of the liquid II and the discharge end of the tube 9. Thus, for any given pressure in the space above'the liquid, the flow of water through the tube 9 into the duct I at venturi 5 will be directly proportional to the Therefore, no liquid will flow as the discharge end of the tube 9 is above the level of thesilquid I I in the float chamber I0. As the engine is started, and air begins to flow through the duct I, the pressure in the throat of the venturi 5 decreases but the pressure in the manifold 8 immediately drops to a lower value so that the pressure above the liquid II in chamber In likewise is reduced and no flow of liquid into the duct I takes place. As the engine speed is increased to a moderate value (above idle conditions), liquid II will begin to flow through pipe 9 into the duct I as the engine load (brake mean effective pressure) is increased as this is represented by an increase in the pressure in he manifold 8, which in turn effects an increase in the pressure in the space above the liquid II in chamber I0. At this point, if the speed is held constant and the load on the engine is increased, the airflow through the duct I will increase as the load increases but the flow of liquid I I becomes greater at an increasing rate because the pressure in the space above the liquid likewise is increasing. Thus the liquid to air ratio is increased as the brake mean effective pressure increases. On the other hand, if the load on the engine is held constant but the speed is increased to a high value, the pressure in manifold 8 will remain constant but pressure in the throat of the lower venturi 24 will become appreciably less than manifold pressure and, therefore, the pressure in the space above the liquid II in chamber I0 will be reduced. This causes the water to air ratio to decrease and at high engine speeds causes the flow of liquid to cease.

It is to be pointed out that in lieu of injecting the anti-detonant liquid into the duct I at the volume of airflow through the duct I to the engine manifold 8.

However, the pressure exertedupon the surface with the volume of airflow through venturi 5 but automatically compensated for variations in the engine brake mean effective pressure and the engine speed.

In operation of the anti-detonant injection system of the present invention, when the engine is at rest, the pressure in the space above the liquid II in the float chamber I 0 will be the same as the pressure on the discharge end of the tube 9 at venturi 5, namely, atmospheric pressure.

throat of the fuel venturi 5 as shown and described, the anti-detonant may be injected at any venturi section that may be provided in the duct I upstream of the throttle I, and while a particular embodiment of the invention has been illustrated and described herein, it is not intended to limit the invention to such disclosure, and changes and modifications may be made therein and thereto within the scope of the claim.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon'or therefor.

I claim:

In an anti-detonant liquid injection system for internal combustion engines having a. manifold through which a fuel mixture is supplied to said engine, a carburetor provided with an air intake duct, in communication with said manifold, a throttle valve positioned in said duct downstream from said carburetor, a section of pipe connecting said air intake duct to said manifold, a first venturi tube positioned in said intake duct upstream from said throttle valve for injecting fuel from said carburetor into said intake duct, a chamber containing anti-detonant liquid with a space thereover, tubular means connected to the throat of said Venturi tube and to said chamber for injecting the anti-detonant liquid into said air intake duct a second Venturi tube having a throat of larger diameter than that of said first Venturi tube positioned in said section of pipe, tube means connecting the throat of said second Venturi tube directly with the space over the anti-detonant liquid in said chamber, means in said chamber operable to maintain the antidetonant liquid therein at a constant level and below the point of injection of said liquid into said air intakeduct, a vent in said chamber providling communication between said space and the exterior atmosphere to thereby bleed atmosplieric air into said chamber, said second Venturi tube producing a suction pressure in said chamber substantially equal to the static manifold pressure at other than relatively high engine speeds and producing a suction pressure at high engine speeds sufilciently low to stop the injec- Number tion of the anti-detonant fluid into said intake \0 duct.

DONALD E. DAHLE.

REFERENCES CITED The following references are of record in the e of this patent:

Number 6 UNITED STATES PATENTS Name Date Stokes Apr. 28, 1931 Meade Mar. 10, 1942 Ericson May 18, 1943 Johnson June 8, 1943 Bodine, Jr. June 5, 1945 FOREIGN PATENTS Country Date France Dec. 19, 1940 

